The present invention relates to a control system, and, more particularly, to a microprocessor-based system for controlling work functions.
There are many work functions carried out that require control according to a predetermined sequence of one or more operating parameters. For example, welding apparatus for various applications is conventionally designed to effect a particular welding sequence by controlling the time of the weld (generally in terms of the number of cycles) and the current level applied (generally in terms of the percent of the maximum available current that can be provided). And, microprocessor-based controllers have been developed that are particularly tailored to control such work functions.
Further, there are applications which require multiple work functions to be controlled in accordance with the predetermined sequence at one, and, often, multiple work stations. And, control systems have been developed which include a master controller programmed to control the overall desired sequence and one or more slave control systems to carry out such work functions in response to the predetermined sequence provided by the master controller.
Unfortunately, as far as is known, while programmable controllers suitable to serve as the master controller are commercially available, such master-slave control systems require the development of slave controllers tailored to the specific work function being controlled. More particularly, for many work functions such as, for example, welding, available controllers are simply not designed to function as slave controllers. Such controllers can thus not be readily used in master-slave control systems. Stated another way, while such commercially available controllers can satisfactorily control a particular work function such as welding, such units cannot be readily utilized with a master controller due to incompatability.
The expense in developing suitable slave controllers tailored to a particular work function can be considerable, as can be the time involved. Moreover, designing a suitable slave controller tailored to a particular work function may not be all that productive unless the application is of sufficient importance to justify the time and expense required.
There is accordingly a need for a master-slave control system capable of controlling work functions which is capable of utilizing available controllers not designed to function as slave controllers. Such a system would obviate the time and expense associated with developing such controllers by allowing utilization of commercially available controllers.